Semiconductor devices are becoming miniaturized, e.g., microminiaturized, and lightweight, e.g., ultra lightweight, by increasing an integration degree of the semiconductor devices. As a semiconductor device is highly integrated, its design rule may decrease. As the design rule decreases, the width and thickness of a metal interconnection in the semiconductor device may be reduced. As a result, however, resistance of the metal interconnection may increase.
Attempts have been made to reduce the resistance of the metal interconnections by using materials having low specific resistance. Materials having low specific resistance, however, may include many limitations. For example, materials having low specific resistance may cause parasitic capacitance between the metal interconnections, thereby reducing reliability of the metal interconnection and of the semiconductor device. Further, some materials having low specific resistance may increase manufacturing costs of the metal interconnections, thereby reducing productivity of the semiconductor device. Therefore, there exists a need for metal interconnections exhibiting improved reliability and operability.